1. Field of the Invention
The present invention pertains to a system and method of upgrading the operating features of a medical device, and, in particular, to a system and method in which an access key associated with both the medical device and the desired set of operating features for that medical device is used to gain access to and set the operating features of that medical device, thereby effectively controlling access to the ability to upgrade the operating features for security, regulatory, and product tracking purposes.
2. Description of the Related Art
A wide variety of electronically controlled medical devices that provide an equally wide variety of medical services, ranging from monitoring the condition of a patient to providing a medical treatment, are known and used everyday throughout the world. Such electronically controlled medical devices are used, for example, in hospitals, physician's offices, clinical sites, an ambulatory environment, as well as in patient's homes to meet the medical needs of the patient. A common feature of all electronically controlled medical devices is that a microprocessor executes an operating routine to control the functionality of the medical device.
Many such electronically controlled medical devices are specifically designed and manufactured so that the finished medical device operates according to a single set of operating features that does not change over the life of the medical device. That is, these devices are capable of executing only one operating routine every time the device is used, with no user selected or input variables. For example, a conventional pulse oximeter monitors a patient's arterial oxygen concentration, a conventional electroencephalograph monitors a patient's brain waves, and a conventional electrocardiograph monitors a patient's heartbeat. The monitoring function of each of these medical devices, which is established by the operating routine executed by the processor in these devices, does not change over the life of the product.
For purposes of the present invention, the phrase “operating feature” refers to any functional capability of the medical device. This includes features that are determined or set at the time of manufacture and cannot be altered by the user. This also includes features of the medical device that can be set, selected, or adjusted by an authorized technician or caregiver, examples of which are discussed in greater detail below.
It can be appreciated that the need may arise for the operating features of a medical device to be upgraded or altered. For example, an error in the operating routine may be discovered after manufacture and need corrected, or later versions or revisions of an operating routine may be developed as technology progresses. Good manufacturing and business practices, as well as government regulations, dictate that manufacturers, sellers or suppliers of medical devices have the ability to track the medical devices they sell. This is important, for example, if the need should arise for the medical devices to be recalled.
If a medical device uses a programmable read-only memory (PROM) to store the operating routine, upgrading the operating features of that device is very burdensome, requiring returning the medical device to the manufacturer or an authorized repair facility. The manufacturer or repair facility must disassemble the unit and physically replace the PROM with an upgraded PROM or other upgraded data storage device. Although this process is burdensome and requires that the patient forgo the use of the medical device while the device is being upgraded, it does allow the manufacturer, supplier, or seller of the medical device to keep track of which medical devices have been upgraded. For example, the manufacturer can create and maintain a database that contains a listing the medical devices and their upgraded status.
If the medical device uses an erasable programmable read-only memory (EPROM) to store the operating routine, also referred to as a flash memory, the device can be upgraded without disassembling the unit. Instead, reprogramming the EPROM can be done using any conventional reprogramming technique via a data port, which is typically provided on the external surface of the housing. While, this significantly simplifies the upgrade process, it can make it more difficult for the manufacturer, supplier, or seller of the medical device to track of which medical devices have been upgraded.
It is common in the medical industry for a manufacturer, supplier, or seller of medical devices to sell or lease a number of identical medical devices to a medical device provider or dealer, who then distributes the medical devices to the doctors' offices, hospitals, or to the patients directly. Upgrading of the medical devices in the medical device provider's or dealer's inventory, or in the field, can be done by the medical device provider/dealer, if the medical device uses an EPROM storage, and if the manufacturer, supplier, or seller provides the upgraded operating routine to the medical device provider/dealer. However, in this situation, the manufacturer of the medical devices has no way of knowing which medical devices in the medical device provider's inventory were actually upgraded by the medical provider. The manufacturer must rely on the medical device provider or dealer actually performing the upgrade to report accurately and reliably which device or devices have been upgraded. As a result, the manufacturer, supplier or seller does not have full control over which medical devices the provider/dealer actually upgrades, what upgrades is made to each device, and cannot track the upgrading of the various devices under the control of the provider/dealer without help from the provider/dealer.
Other electronically controlled medical devices exist in which at least some of the operating features of the medical device can be set after the device has been manufactured. For example, it is well know to use a pressure support system to provide a flow of gas to an airway of a patient at an elevated pressure via a patient circuit to treat a medical disorder. One such system, known as a continuous positive airway pressure (CPAP) device, supplies a flow of breathing gas at a constant positive pressure to the airway of a patient throughout the patient's breathing cycle to treat obstructive sleep apnea (OSA), cheynes-stokes respiration, congestive heart failure, central sleep apnea, as well as other cardio-respiratory disorders.
The ability of a pressure support system to provide a continuous pressure, as opposed, for example, to a variable pressure, is an operating feature of the system that is determined at the time of manufacture. The specific CPAP pressure that the device is to deliver, which is typically not set when the device leaves the manufacturer, is an example of an operating feature of the system that is determined after manufacture. Instead, the CPAP pressure is set to a prescription level once a patient has been prescribed the CPAP device. Setting the CPAP pressure is accomplished, for example, by manually setting a switch, dial, knob or other input device associated with the medical device. If the CPAP operates according an operating routine stored on an EPROM, setting the CPAP pressure can be accomplished by downloading the CPAP pressure as an operating feature directly into the controller or the memory of the medical device via a dedicated RS232 port.
A conventional ventilator, such as the ESPRIT® Ventilator manufactured by Respironics of Pittsburgh, Pa., is an example of a pressure support system in which the pressure of gas delivered to the patient varies between inspiration and expiration so as to replace or supplement the patient's own ventilation. For purposes of the present invention, the phase “pressure support system” or “pressure support device” includes any medical system or device, invasive or non-invasive, that delivers a flow of breathing gas to the airway of a patient, including a ventilator.
A conventional ventilator is capable of operating in a variety of ventilatory modes, where each mode corresponds to a different technique by which the ventilator controls its four basic ventilator operations. These four basic operations are: 1) determining of the trigger point, which is the transition from the expiratory to the inspiratory phase of the ventilatory cycle, 2) controlling the ventilator during the inspiratory phase where the ventilator delivers the flow of breathing gas, 3) determining the cycle point, which is the transition from the inspiratory phase to the expiratory phase, and 4) controlling the ventilator during the expiratory phase.
What the ventilator does in each mode of ventilation is typically determined at the time of manufacture, so that the ventilator always operates the same way each time a particular ventilatory mode is selected. However, which ventilatory mode the ventilator is to operate in, and the particular parameters of that mode, are generally not set when the ventilator leaves the factory. These operating features are set by the caregiver based on the needs of the patient when the patient begins using the ventilator. What the ventilator does in each ventilator mode, the selection of which mode to operate in, and the selectable parameters associated with each mode are considered the operating features of the ventilator for present purposes.
It is known to provide a pressure support device in which the pressure of the breathing gas delivered to the patient varies in synchronization with the patient's breathing cycle, so that a lower pressure is delivered to the patient during the expiratory phase of the breathing cycle than is delivered during the inspiratory phase. As a result, the patient receives the necessary pressure support during inspiration to treat their disorder, such as OSA, but is not breathing out against a relatively high pressure during expiration, which can be uncomfortable to some patients. This mode of pressure support is typically referred to as “bi-level” pressure support.
With bi-level pressure support, the patient's inspiratory positive airway pressure (IPAP), expiratory positive airway pressure (EPAP), and how the device detects and compensates for system leaks, if any, are examples of operating features of the pressure support system. Bi-level pressure support is taught, for example, in U.S. Pat. No. 5,148,802 to Sanders et al., U.S. Pat. No. 5,313,937 to Zdrojkowski et al., U.S. Pat. No. 5,433,193 to Sanders et al., U.S. Pat. No. 5,632,269 to Zdrojkowski et al., U.S. Pat. No. 5,803,065 to Zdrojkowski et al., and U.S. Pat. No. 6,029,664 to Zdrojkowski et al., the contents of each of which are incorporated by reference into the present invention.
It is further known to provide a pressure support therapy in which the pressure provided to the patient changes based on the detected conditions of the patient, such as whether the patient is snoring or experiencing an apnea, hypopnea, upper airway resistance, or a combination thereof. This mode of pressure support is typically referred to as an “auto-titration” mode, because the pressure support device itself determines the optimum pressure to deliver to the patient. With this type of pressure support system, the operating features typically include a maximum and/or minimum pressure that can be output by the device, which is set once the pressure support system has been prescribed to a patient, and the technique by which the system alters the patient pressure, which is typically set at the time of manufacture.
An example of an auto-titration pressure support system that adjusts the pressure delivered to the patient based on whether or not the patient is snoring is the Virtuoso® CPAP family of devices manufactured and distributed by Respironics, Inc. This auto-titration pressure support mode is taught in U.S. Pat. Nos. 5,203,343; 5,458,137 and 6,087,747 all to Axe et al., the contents of which are incorporated herein by reference. An example of a pressure support device that actively tests the patient's airway to determine whether obstruction, complete or partial, could occur and adjusts the pressure output to avoid this result is the Tranquility® Auto CPAP device, also manufactured and distributed by Respironics, Inc. This auto-titration pressure support mode is taught in U.S. Pat. No. 5,645,053 to Remmers et al., the content of which is incorporated herein by reference.
Other pressure support systems that offer other modes of providing positive pressure to the patient are also known. For example, a proportional assist ventilation (PAV®) mode of pressure support provides a positive pressure therapy in which the pressure of gas delivered to the patient varies with the patient's breathing effort to increase the comfort to the patient. U.S. Pat. Nos. 5,044,362 and 5,107,830 both to Younes, the contents of which are incorporated herein by reference, teach a pressure support device capable of operating in a PAV mode. Proportional positive airway pressure (PPAP) devices deliver breathing gas to the patient based on the flow generated by the patient. U.S. Pat. Nos. 5,535,738; 5,794,615; and 6,105,573 all to Estes et al., the contents of which are incorporated herein by reference, teach a pressure support device capable of operating in a PPAP mode. In the PAV and PPAP pressure support systems, the percent of assistance provided by the unit is at least one of the operating features of the pressure support device that is set after the device has been prescribed for use by a patient.
It should be noted that, as a medical device, the operating features of a pressure support system are normally determined for each patient under strict medical supervision to ensure that each patient receives the appropriate pressure support treatment for his or her condition. Prescribing a pressure support treatment for a patient is analogous to prescribing a medication necessary to cure the patient's ailment. However, instead of receiving medicine, the patient receives a durable medical product, such as a CPAP device, to treat his or her condition. As with a medication prescription, the patient's pressure support prescription should not be altered, except under a doctor's prescription, and must be followed, as prescribed, in order for the pressure support treatment to be effective. For these reasons, access to the ability to change the operating features of the medical device must be tightly controlled to prevent unauthorized tampering or inadvertent modification, which can be detrimental to the patient's health or reduce the efficacy of the treatment.
Other operating features include enabling or disabling additional features of the pressure support device, such as alarms, the ability to provide a time backup breath, which is a ventilatory breath that is delivered to the patient if he or she does not spontaneously initiate a breathing within a set period of time. A further operating feature common in many pressure support devices is a pressure ramp, which is a feature in which the pressure level provided to the patient is gradually increased over time. This is done, for example, to allow the patient to fall asleep under a relatively low pressure or to provide a comfortable transition from an initial low pressure to the desired therapeutic pressure. The duration of the ramp period is also an operating feature of a pressure support device. As with the operating features associated with the prescription pressure discussed above, activating, deactivating or altering other features of the pressure support system is preferably and, in many cases, necessarily done by an authorized caregiver or technician under the direction and/or supervision of the physician or other caregiver responsible for that patient.
As noted above, for purposes of the present invention, the operating features of the pressure support system include the type of pressure support treatment or mode provided to the patient by the pressure support system, e.g., CPAP, bi-level, auto-titration, PPAP, PAV, or a combination thereof. While a great number of pressure support systems can only operate in one pressure support mode, some conventional pressure support systems can operate in different pressure support modes depending on how the flexibility of the system. For example, a typical bi-level pressure support system can operate as a CPAP device if the IPAP and EPAP levels are the same. As noted above, a conventional ventilator is also typically capable of operating in one of several ventilatory modes.
Once a patient is prescribed a pressure support treatment, to minimize cost, he or she will receive or will purchase or lease a pressure support device that is only capable of operating in that pressure support mode. For example, it would not be economical or practical to issue a pressure support device capable of delivering bi-level pressure support to a patient who needs only a CPAP pressure support therapy, especially since the patient may need to be switched to a bi-level pressure support therapy.
On the other hand, it can be appreciated that for some patients, the need may arise for the medical device they are using to be switched to a different operating features over the course of their diagnosis and/or treatment. For example, it is also not uncommon to need to change the prescription pressure output by the pressure support device, the duration of the pressure ramp, or other the features of the system, over the course of the patient's support therapy. It is also not uncommon for an OSA sufferer to initially be treated with a CPAP device, and, thereafter, switched to a bi-level device in order to increase their comfort and compliance with the pressure support therapy. In addition, in certain situations, medical reimbursement policies dictate that a patient be treated with a first type of pressure support therapy before a reimbursement will be authorized for a second type of therapy.
However, as noted above, current techniques for upgrading a medical device do not provide the ability of the medical device manufacture, supplier, or seller to track and control the upgrade of medical devices done by someone beyond their control, such as a medical device provider or dealer who buys medical devices from the manufacturer. This is particularly the case for those features of a medical device that are intended to be altered after manufacture.
For example, a conventional bi-level pressure support system provides the ability to set the IPAP and EPAP pressure to be delivered to the patient. However, other than operating the bi-level device as a CPAP device, as discussed above, changing the bi-level device to any other mode of pressure support, such as a PPAP, auto-titration, or PAV, or to provide a timed backup breath or other feature not already included in the device, involves the same tracking and control problems discussed above with upgrading a PROM-based medical device.